heavy cavalry engaging heavy cavalry

[Urselius]

I was wanting to use Newton's original terms. Momentum yes, but the force exerted is due to the change in velocity when a moving object hits a target. When it is moving at a constant velocity, no force is acting on a object - deceleration, which is kinetically equivalent to acceleration, converts the momentum into the force acting on the target. Though horses don't act exactly like missiles in a vacuum!

Military thought, up to c.1750 considered the weight of the horse to be the determining factor in charges - the side with the heavier horses would win. The standard charger of the period was the "black horse" (not always black in colour), you can see them in illustrations of Marlborough's wars - large bodied, though quite short-coupled horses, with great square hindquarters, thick highly curved necks and small heads. After this time the realisation that momentum - speed and mass combined - was the important thing and warm blooded horses, of slighter build and higher speed tended to replace the old "black horse" chargers. What sort of ideas the Ancients entertained on horse form and use in cavalry charges we don't know. We don't know if they had a gradation of paces - trot - canter -gallop as they closed with an enemy as some later regulations stipulated.